Scientists have come one step closer to understanding the mysterious science of sleep by uncovering a chemical critical in inducing drowsiness.

Researchers at Tufts University School of Medicine studied mice and determined that brain cells called astrocytes made the mice sleepy by releasing a sleep-inducing chemical called adenosine.

The study, published in the journal Neuron, is unique because it marks the first time a non-neuronal cell in the brain has been shown to influence behavior, according to a researcher. Live Science explains: “Unlike neurons, astrocytes do not fire electrical spikes, and they are often thought of as simply support cells.”

Identifying the crucial role astrocytes play may facilitate the creation of new drugs that can help bring on sleep or keep it at bay, depending on patient needs.

In 2004, a team led by the chief of neurobiology research at the Veterans Affairs Greater Los Angeles Healthcare System conducted a major study of three brain chemicals known to govern sleep behavior. The study, also published in Neuron, determined that serotonin and norepinephrine affect muscle tone and keep the body from moving while asleep, while histamine has an effect on wakefulness.

Sleep appears to be one of the most important human functions, but scientists have traditionally understood very little about it. Nevertheless, a general understanding of the need for sleep and its benefits has emerged, and researchers agree that sleep is necessary for the rejuvenation of the brain—though the exact benefits are not clear.

Some sleep experts believe that, during sleep, the brain reviews and combines the various streams of information it collected during the day. Another theory suggests that sleep allows the brain to refuel and clear out waste. Some experts even contend that sleep allows people to master specific tasks like riding a bicycle or playing a musical instrument.

The most convincing evidence of the importance of sleep is anecdotal: the effects of sleep deprivation can be seriously damaging, leaving no doubt as to the necessity of proper rest.

According to the BBC, a continued lack of sleep affects our ability to control language, memory, planning and even our sense of time: “17 hours of sustained wakefulness leads to a decrease in performance equivalent to a blood alcohol level of 0.05%,” or the legal drinking limit in the U.K., which is the equivalent of two glasses of wine.

One boy has provided living proof of the damage inflicted by sleep deprivation. Until recently, 3-year-old Rhett Lamb was unable to sleep more than 2 hours a day, long after his body and mind had become fatigued. Rhett’s mother told ABC News, “He couldn’t play, he didn’t interact with other children. His frustration level was so high, and it just kept getting worse and worse and worse. He couldn’t communicate with anyone. It was heartbreaking.”

Doctors diagnosed the condition as Chiari malformation, a condition in which a section of the brain called the cerebellum extends from the bottom of the skull and exerts pressure on the spinal cord and the rest of the brain. Although there is no cure for Chiari, doctors operated on Rhett and surgery reduced many of his symptoms. He has since begun to sleep normal hours and is catching up developmentally with his peers.